Monolithic LED array structure

ABSTRACT

A wavelength converting layer is partially diced to generate a first and second wavelength converting layer segment and to allow partial isolation between the first segment and the second segment such that the wavelength converting layer segments are connected by a connecting wavelength converting layer. The first and second wavelength converting layer segments are attached to a first and second light emitting device, respectively to create a first and second pixel. The connecting wavelength converting layer segment is removed to allow complete isolation between the first pixel and the second pixel. An optical isolation material is applied to exposed surfaces of the first and second pixel and a sacrificial portion of the wavelength converting layer segments and optical isolation material attached to the sacrificial portion is removed from a surface facing away from the first light emitting device, to expose a emitting surface of the first wavelength converting layer segment.

BACKGROUND

Precision control lighting applications can require the production andmanufacturing of small addressable light emitting diode (LED) pixelsystems. Manufacturing such LED pixel systems can require accuratedeposition of material due to the small size of the pixels and the smalllane space between the systems. Semiconductor light-emitting devicesincluding LEDs, resonant cavity light emitting diodes (RCLEDs), verticalcavity laser diodes (VCSELs), and edge emitting lasers are among themost efficient light sources currently available. Materials systemscurrently of interest in the manufacture of high-brightness lightemitting devices capable of operation across the visible spectruminclude Group III-V semiconductors, particularly binary, ternary, andquaternary alloys of gallium, aluminum, indium, and nitrogen, alsoreferred to as III-nitride materials. Typically, III-nitride lightemitting devices are fabricated by epitaxially growing a stack ofsemiconductor layers of different compositions and dopant concentrationson a sapphire, silicon carbide, III-nitride, composite, or othersuitable substrate by metal-organic chemical vapor deposition (MOCVD),molecular beam epitaxy (MBE), or other epitaxial techniques. The stackoften includes one or more n-type layers doped with, for example, Si,formed over the substrate, one or more light emitting layers in anactive region formed over the n-type layer or layers, and one or morep-type layers doped with, for example, Mg, formed over the activeregion. Electrical contacts are formed on the n- and p-type regions.

III-nitride devices are often formed as inverted or flip chip devices,where both the n- and p-contacts formed on the same side of thesemiconductor structure, and most of the light is extracted from theside of the semiconductor structure opposite the contacts.

SUMMARY

A wavelength converting layer is partially diced to generate a first andsecond wavelength converting layer segment and to allow partialisolation between the first segment and the second segment such that thewavelength converting layer segments are connected by a connectingwavelength converting layer. The first and second wavelength convertinglayer segments are attached to a first and second light emitting device,respectively to create a first and second pixel. The connectingwavelength converting layer segment is removed to allow completeisolation between the first pixel and the second pixel. An opticalisolation material is applied to exposed surfaces of the first andsecond pixel and a sacrificial portion of the wavelength convertinglayer segments and optical isolation material attached to thesacrificial portion is removed from a surface facing away from the firstlight emitting device, to expose a emitting surface of the firstwavelength converting layer segment.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A is a top view illustration of an LED array with an explodedportion;

FIG. 1B is a cross sectional illustration of an LED array with trenches;

FIG. 1C is a perspective illustration of another LED array withtrenches;

FIG. 1D is a flow diagram for generating pixels in a LED array;

FIG. 1E is a cross-section view diagram of generating pixels in an LEDarray;

FIG. 1F is another flowchart of a process to generate pixels in an LEDarray;

FIG. 1G is another cross-section view diagram of generating pixels in anLED array;

FIG. 1H is a cross-section view diagram of an LED array;

FIG. 2A is a top view of the electronics board with LED array attachedto the substrate at the LED device attach region in one embodiment;

FIG. 2B is a diagram of one embodiment of a two channel integrated LEDlighting system with electronic components mounted on two surfaces of acircuit board;

FIG. 2C is an example vehicle headlamp system; and

FIG. 3 shows an example illumination system.

DETAILED DESCRIPTION

Examples of different light illumination systems and/or light emittingdiode (“LED”) implementations will be described more fully hereinafterwith reference to the accompanying drawings. These examples are notmutually exclusive, and features found in one example may be combinedwith features found in one or more other examples to achieve additionalimplementations. Accordingly, it will be understood that the examplesshown in the accompanying drawings are provided for illustrativepurposes only and they are not intended to limit the disclosure in anyway. Like numbers refer to like elements throughout.

It will be understood that, although the terms first, second, third,etc. may be used herein to describe various elements, these elementsshould not be limited by these terms. These terms may be used todistinguish one element from another. For example, a first element maybe termed a second element and a second element may be termed a firstelement without departing from the scope of the present invention. Asused herein, the term “and/or” may include any and all combinations ofone or more of the associated listed items.

It will be understood that when an element such as a layer, region, orsubstrate is referred to as being “on” or extending “onto” anotherelement, it may be directly on or extend directly onto the other elementor intervening elements may also be present. In contrast, when anelement is referred to as being “directly on” or extending “directlyonto” another element, there may be no intervening elements present. Itwill also be understood that when an element is referred to as being“connected” or “coupled” to another element, it may be directlyconnected or coupled to the other element and/or connected or coupled tothe other element via one or more intervening elements. In contrast,when an element is referred to as being “directly connected” or“directly coupled” to another element, there are no intervening elementspresent between the element and the other element. It will be understoodthat these terms are intended to encompass different orientations of theelement in addition to any orientation depicted in the figures.

Relative terms such as “below,” “above,” “upper,”, “lower,” “horizontal”or “vertical” may be used herein to describe a relationship of oneelement, layer, or region to another element, layer, or region asillustrated in the figures. It will be understood that these terms areintended to encompass different orientations of the device in additionto the orientation depicted in the figures.

Semiconductor light emitting devices (LEDs) or optical power emittingdevices, such as devices that emit ultraviolet (UV) or infrared (IR)optical power, are among the most efficient light sources currentlyavailable. These devices (hereinafter “LEDs”), may include lightemitting diodes, resonant cavity light emitting diodes, vertical cavitylaser diodes, edge emitting lasers, or the like. Due to their compactsize and lower power requirements, for example, LEDs may be attractivecandidates for many different applications. For example, they may beused as light sources (e.g., flash lights and camera flashes) forhand-held battery-powered devices, such as cameras and cell phones. Theymay also be used, for example, for automotive lighting, heads up display(HUD) lighting, horticultural lighting, street lighting, torch forvideo, general illumination (e.g., home, shop, office and studiolighting, theater/stage lighting and architectural lighting), augmentedreality (AR) lighting, virtual reality (VR) lighting, as back lights fordisplays, and IR spectroscopy. A single LED may provide light that isless bright than an incandescent light source, and, therefore,multi-junction devices or arrays of LEDs (such as monolithic LED arrays,micro LED arrays, etc.) may be used for applications where morebrightness is desired or required.

According to embodiments of the disclosed subject matter, LED arrays(e.g., micro LED arrays) may include an array of pixels as shown inFIGS. 1A, 1B, and/or 1C. LED arrays may be used for any applicationssuch as those requiring precision control of LED array segments. Pixelsin an LED array may be individually addressable, may be addressable ingroups/subsets, or may not be addressable. In FIG. 1A, a top view of aLED array 110 with pixels 111 is shown. An exploded view of a 3×3portion of the LED array 110 is also shown in FIG. 1A. As shown in the3×3 portion exploded view, LED array 110 may include pixels 111 with awidth w₁ of approximately 100 μm or less (e.g., 40 μm). The lanes 113between the pixels may be separated by a width, w₂, of approximately 20μm or less (e.g., 5 μm). The lanes 113 may provide an air gap betweenpixels or may contain other material, as shown in FIGS. 1B and 1C andfurther disclosed herein. The distance d₁ from the center of one pixel111 to the center of an adjacent pixel 111 may be approximately 120 μmor less (e.g., 45 μm). It will be understood that the widths anddistances provided herein are examples only, and that actual widthsand/or dimensions may vary.

It will be understood that although rectangular pixels arranged in asymmetric matrix are shown in FIGS. 1A, B and C, pixels of any shape andarrangement may be applied to the embodiments disclosed herein. Forexample, LED array 110 of FIG. 1A may include, over 10,000 pixels in anyapplicable arrangement such as a 100×100 matrix, a 200×50 matrix, asymmetric matrix, a non-symmetric matrix, or the like. It will also beunderstood that multiple sets of pixels, matrixes, and/or boards may bearranged in any applicable format to implement the embodiments disclosedherein.

FIG. 1B shows a cross section view of an example LED array 1000. Asshown, the pixels 1010, 1020, and 1030 correspond to three differentpixels within an LED array such that a separation sections 1041 and/orn-type contacts 1040 separate the pixels from each other. According toan embodiment, the space between pixels may be occupied by an air gap.As shown, pixel 1010 includes an epitaxial layer 1011 which may be grownon any applicable substrate such as, for example, a sapphire substrate,which may be removed from the epitaxial layer 1011. A surface of thegrowth layer distal from contact 1015 may be substantially planar or maybe patterned. A p-type region 1012 may be located in proximity to ap-contact 1017. An active region 1021 may be disposed adjacent to then-type region and a p-type region 1012. Alternatively, the active region1021 may be between a semiconductor layer or n-type region and p-typeregion 1012 and may receive a current such that the active region 1021emits light beams. The p-contact 1017 may be in contact with SiO2 layers1013 and 1014 as well as plated metal (e.g., plated copper) layer 1016.The n type contacts 1040 may include an applicable metal such as Cu. Themetal layer 1016 may be in contact with a contact 1015 which may bereflective.

Notably, as shown in FIG. 1B, the n-type contact 1040 may be depositedinto trenches 1130 created between pixels 1010, 1020, and 1030 and mayextend beyond the epitaxial layer. Separation sections 1041 may separateall (as shown) or part of a converter material 1050. It will beunderstood that a LED array may be implemented without such separationsections 1041 or the separation sections 1041 may correspond to an airgap. The separation sections 1041 may be an extension of the n-typecontacts 1040, such that, separation sections 1041 are formed from thesame material as the n-type contacts 1040 (e.g., copper). Alternatively,the separation sections 1041 may be formed from a material differentthan the n-type contacts 1040. According to an embodiment, separationsections 1041 may include reflective material. The material inseparation sections 1041 and/or the n-type contact 1040 may be depositedin any applicable manner such as, for example, but applying a meshstructure which includes or allows the deposition of the n-type contact1040 and/or separation sections 1041. Converter material 1050 may havefeatures/properties similar to wavelength converting layer 205 of FIG.2A. As noted herein, one or more additional layers may coat theseparation sections 1041. Such a layer may be a reflective layer, ascattering layer, an absorptive layer, or any other applicable layer.One or more passivation layers 1019 may fully or partially separate then-contact 1040 from the epitaxial layer 1011.

The epitaxial layer 1011 may be formed from any applicable material toemit photons when excited including sapphire, SiC, GaN, Silicone and maymore specifically be formed from a III-V semiconductors including, butnot limited to, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP,InAs, InSb, II-VI semiconductors including, but not limited to, ZnS,ZnSe, CdSe, CdTe, group IV semiconductors including, but not limited toGe, Si, SiC, and mixtures or alloys thereof. These examplesemiconductors may have indices of refraction ranging from about 2.4 toabout 4.1 at the typical emission wavelengths of LEDs in which they arepresent. For example, III-Nitride semiconductors, such as GaN, may haverefractive indices of about 2.4 at 500 nm, and III-Phosphidesemiconductors, such as InGaP, may have refractive indices of about 3.7at 600 nm. Contacts coupled to the LED device 200 may be formed from asolder, such as AuSn, AuGa, AuSi or SAC solders.

The n-type region may be grown on a growth substrate and may include oneor more layers of semiconductor material that include differentcompositions and dopant concentrations including, for example,preparation layers, such as buffer or nucleation layers, and/or layersdesigned to facilitate removal of the growth substrate. These layers maybe n-type or not intentionally doped, or may even be p-type devicelayers. The layers may be designed for particular optical, material, orelectrical properties desirable for the light emitting region toefficiently emit light. Similarly, the p-type region 1012 may includemultiple layers of different composition, thickness, and dopantconcentrations, including layers that are not intentionally doped, orn-type layers. An electrical current may be caused to flow through thep-n junction (e.g., via contacts) and the pixels may generate light of afirst wavelength determined at least in part by the bandgap energy ofthe materials. A pixel may directly emit light (e.g., regular or directemission LED) or may emit light into a wavelength converting layer 1050(e.g., phosphor converted LED, “POLED”, etc.) that acts to furthermodify wavelength of the emitted light to output a light of a secondwavelength.

Although FIG. 1B shows an example LED array 1000 with pixels 1010, 1020,and 1030 in an example arrangement, it will be understood that pixels inan LED array may be provided in any one of a number of arrangements. Forexample, the pixels may be in a flip chip structure, a verticalinjection thin film (VTF) structure, a multi-junction structure, a thinfilm flip chip (TFFC), lateral devices, etc. For example, a lateral LEDpixel may be similar to a flip chip LED pixel but may not be flippedupside down for direct connection of the electrodes to a substrate orpackage. A TFFC may also be similar to a flip chip LED pixel but mayhave the growth substrate removed (leaving the thin film semiconductorlayers un-supported). In contrast, the growth substrate or othersubstrate may be included as part of a flip chip LED.

The wavelength converting layer 1050 may be in the path of light emittedby active region 1021, such that the light emitted by active region 1021may traverse through one or more intermediate layers (e.g., a photoniclayer). According to embodiments, wavelength converting layer 1050 ormay not be present in LED array 1000. The wavelength converting layer1050 may include any luminescent material, such as, for example,phosphor particles in a transparent or translucent binder or matrix, ora ceramic phosphor element, which absorbs light of one wavelength andemits light of a different wavelength. The thickness of a wavelengthconverting layer 1050 may be determined based on the material used orapplication/wavelength for which the LED array 1000 or individual pixels1010, 1020, and 1030 is/are arranged. For example, a wavelengthconverting layer 1050 may be approximately 20 μm, 50 μm or 200 μm. Thewavelength converting layer 1050 may be provided on each individualpixel, as shown, or may be placed over an entire LED array 1000.

Primary optic 1022 may be on or over one or more pixels 1010, 1020,and/or 1030 and may allow light to pass from the active region 101and/or the wavelength converting layer 1050 through the primary optic.Light via the primary optic may generally be emitted based on aLambertian distribution pattern such that the luminous intensity of thelight emitted via the primary optic 1022, when observed from an idealdiffuse radiator, is directly proportional to the cosine of the anglebetween the direction of the incident light and the surface normal. Itwill be understood that one or more properties of the primary optic 1022may be modified to produce a light distribution pattern that isdifferent than the Lambertian distribution pattern.

Secondary optics which include one or both of the lens 1065 andwaveguide 1062 may be provided with pixels 1010, 1020, and/or 1030. Itwill be understood that although secondary optics are discussed inaccordance with the example shown in FIG. 1B with multiple pixels,secondary optics may be provided for single pixels. Secondary optics maybe used to spread the incoming light (diverging optics), or to gatherincoming light into a collimated beam (collimating optics). Thewaveguide 1062 may be coated with a dielectric material, a metallizationlayer, or the like and may be provided to reflect or redirect incidentlight. In alternative embodiments, a lighting system may not include oneor more of the following: the wavelength converting layer 1050, theprimary optics 1022, the waveguide 1062 and the lens 1065.

Lens 1065 may be formed form any applicable transparent material suchas, but not limited to SiC, aluminum oxide, diamond, or the like or acombination thereof. Lens 1065 may be used to modify the a beam of lightto be input into the lens 1065 such that an output beam from the lens1065 will efficiently meet a desired photometric specification.Additionally, lens 1065 may serve one or more aesthetic purpose, such asby determining a lit and/or unlit appearance of the multiple LED devices200B.

FIG. 1C shows a cross section of a three dimensional view of a LED array1100. As shown, pixels in the LED array 1100 may be separated bytrenches which are filled to form n-contacts 1140. The pixels may begrown on a substrate 1114 and may include a p-contact 1113, a p-GaNsemiconductor layer 1112, an active region 1111, and an n-Gansemiconductor layer 1110. It will be understood that this structure isprovided as an example only and one or more semiconductor or otherapplicable layers may be added, removed, or partially added or removedto implement the disclosure provided herein. A converter material 1117may be deposited on the semiconductor layer 1110 (or other applicablelayer).

Passivation layers 1115 may be formed within the trenches 1130 andn-contacts 1140 (e.g., copper contacts) may be deposited within thetrenches 1130, as shown. The passivation layers 1115 may separate atleast a portion of the n-contacts 1140 from one or more layers of thesemiconductor. According to an implementation, the n-contacts 1140, orother applicable material, within the trenches may extend into theconverter material 1117 such that the n-contacts 1140, or otherapplicable material, provide complete or partial optical isolationbetween the pixels.

Techniques disclosed herein include dicing and/or wafer levelsegmentation which may include generating or providing a grown orotherwise manufacturing LED components such as, but not limited to, asemiconductor layer, n-type material, p-type material, convertermaterial, die, carrier material, or the like or a combination thereof.The component may be cured or may be treated with a temperature basedtreatment, chemical treatment, or other treatment. The component may bediced such that two or more segments of the component result from thedicing process. The segments may be completely isolated or may bepartially isolated from each other. The segments may include asubstantially uniform material or may include multiple materials. Thesegments may undergo additional treatments/process and may be cleanedthrough a, for example, chemical, ultrasonic, or other applicablecleaning process.

The subject matter disclosed herein may be applied to generating arrayswith sub-500 micron pixels and sub-100 micron components. Pixels in LEDarrays with sidewalls covered by optical isolation materials may begenerated using the techniques disclosed herein.

As used herein, dice, dicing, or diced may correspond to or refer to anyapplicable manner of segmenting, dividing, apportioning, slicing,compartmentalizing, or the like, or by dicing as understood in the art.A component may be diced by any applicable manner such as sawing,etching, applying a mask to dice, using one or more lasers, chemicaltreatment, or the like.

FIG. 1D shows a method 1200 for generating pixels in an LED array,according to the subject matter disclosed herein. The pixels in such aLED array may be sub-500 micron large such as, for example, having awidth of approximately 100 microns. A wavelength converting layer may beattached to a carrier layer and, at step 1220, the two attached layersmay be diced such that they are divided into multiple segments separatedby gaps between the segments. The wavelength converting layer may beremoved from the space between the segments such that there is nowavelength converting layer in the gaps. Part of the carrier layer maybe removed within each gap area and part of the carrier layer may remainin a contiguous manner such that the segments are connected by thecontiguous parts of the carrier layer that are not removed during thesegmentation. At step 1230, the segments may be aligned with lightemitting devices and attached to the light emitting devices to createpixels. At step 1240, the portion of the carrier layer connecting two ormore segments may be removed such that the segments are no longerconnected via the carrier layer. At step 1250, an optical isolationmaterial may be applied to the exposed surfaces of the pixels. At step1260, the carrier layer and any corresponding optical isolation materialthat is attached to the surface of the carrier layer may be removed,resulting in a pixel that includes the light emitting device andwavelength converting layer along with the optical isolation material onthe sidewalls of the light-emitting device and wavelength convertinglayer.

A wavelength converting layer may contain material configured to convertone or more properties of light, as disclosed herein. The wavelengthconverting layer may convert a property of light, such as, but notlimited to, its wavelength, its phase, or the like.

A carrier layer may contain, but is not limited to, any material thathas a coefficient of thermal expansion (CTE) that is substantiallymatched to the CTE of the wavelength converting layer. Additionally, acarrier layer may contain material that is able to undergo thetemperature requirements of an atomic layer deposition (ALD) process.The softening temperature of the carrier layer may be higher than thesoftening temperature of the wavelength converting layer. Asnon-limiting examples, the carrier layer may be an alumosilicate glassand may have a CTE of 8.7 ppm/K with a softening temperature of 827° C.or, alternatively, the carrier layer may a glass and have a CTE of 9.4ppm/K with a softening temperature of 724° C. The carrier layer may be aglass layer, a ceramic layer, or the like.

An optical isolation material may be any applicable optically modifyingmaterial such as a distributed Bragg reflector (DBR) layer(s),reflective material, absorptive material, or the like. As specificexamples, the optical isolation material may include stainless steel oraluminum. DBR layers may include, but are not limited to, layers of SiO₂and TiO₂; SiO₂ and ZrO₂; SiC and MgO; SiC and Silica; GaAs and AlAs;ITO, or the like.

As shown in FIG. 1E at (a), a carrier layer 1320 may be attached to awavelength converting layer 1310. The carrier layer 1320 may be attachedto wavelength converting layer 1310 via any applicable techniqueincluding attachment via an adhesive material.

According to step 1220 of FIG. 1D, as shown in FIG. 1E at (b), thecarrier layer 1320 attached to wavelength converting layer 1310 may bediced to create gaps 1315 between the segments. As shown in FIG. 1E at(b), the gaps 1315 between the segments may not contain the wavelengthconverting layer 1310 and may extend into the carrier layer 320. Toclarify, the wavelength converting layer 1310 of a first segment may becompletely isolated by the wavelength converting layer 1310 of a secondsegment such that the gap is provided between the wavelength convertinglayer 1310 of the first segment and the wavelength converting layer 1310of the second segment. A contiguous portion of the carrier layer 1320may remain and may connect the segments.

According to step 1230 of FIG. 1D, as shown in FIG. 1E at (c), thesegmented carrier layer 1320 and wavelength converting layer 1310 may bealigned with and attached to light emitting devices 1330. The gaps 1315between the segmented layers may correspond to the required spacingbetween the light emitting devices 1330 such that the segmented layerscan be aligned with and attached to the light emitting devices 1330.Light emitting device 1330 may contain an active light-emitting layerand may also contain n-contacts and p-contacts that enable current toactivate the active light-emitting layer. The carrier layers 1320,wavelength converting layer 1310 and light emitting devices 1330 may becured via any applicable technique such as temperature based curing,polymer based curing, UV based curing, or the like.

According to step 1240 of FIG. 1D, as shown in FIG. 1E at (d), a portionof the carrier layer 1320 may be removed such that at least thecontiguous portion of the carrier layer 1320 that connected the segmentsis removed. The portion of carrier layer 1320 may be removed using anyapplicable technique including via sawing, etching, applying a mask todice, using one or more lasers, chemical treatment, or the like, or bydicing as understood in the art. The dicing may result in individualpixels that contain light emitting devices 1330, wavelength convertinglayers, 1320, and a portion of the carrier layer 1320 such that thepixels are not connected via the carrier layer 1320.

As shown in FIG. 1E at (d), the light emitting devices 1330 with thesegmented wavelength converting layer 1310 and carrier layer 1320(collectively, pixels) may be placed on a tape 1335 which may beconfigured to restrict the leakage of gas particles. As an example, thetape 1335 may be a kapton tape. According to step 1250 of FIG. 1D, anoptical isolation material 1340 may be applied to the pixels. Theoptical isolation material may be applied via an atomic layer deposition(ALD) process. ALD is a technique whereby a material may be depositedonto a surface in a self-limiting manner such that a thin coating orlayer of the material is deposited into the surface. As shown in FIG. 1Eat (d), an optical isolation material 1340 may be deposited onto theexposed surfaces of the pixels including the sidewalls of the lightemitting devices 1330, the sidewalls of the wavelength converting layers1310 and the sidewall and top surface of the carrier layers 1320.

As shown in FIG. 1E at (e) the pixels may be deposited onto a tape 1345configured to support component removal techniques. According to animplementation, tape 1335 and 1345 may be the same tape. According tostep 1260 of FIG. 1D, carrier layer 1320 as well as the opticalisolation material 1340 on the top surface and sidewalls of the carrierlayer 1320 may be removed. The removal may be conducted via sawing,etching, applying a mask to dice, using one or more lasers, chemicaltreatment, or the like, or dicing as understood in the art. Theresulting pixel may contain light emitting devices 1330 with opticalisolation material on their sidewalls and wavelength converting layers1310 with optical isolation material on their sidewalls. As shown, thesurface of the wavelength converting layers 1310 opposite the lightemitting devices 1330 do not contain the optical isolation material andthe pixels may be configured to emit light through this surface.

According to an implementation of the disclosed subject matter, as shownin FIG. 1F at step 1410 and in FIG. 1G at (b), a wavelength convertinglayer 1510 of FIG. 1G (a) may be partially diced to segment thewavelength converting layer 1510 into multiple segments. The dicing mayresult in gaps 1515 between the segments. As shown in FIG. 1G at (b),the gaps 1315 between the segments may not contain the wavelengthconverting layer 1510. A contiguous portion of the wavelength convertinglayer 1510 may remain and may connect the segments such that the dicingresults in partial isolation between the multiple segments that areconnected by a connecting segment of the wavelength converting layer.

According to step 1420 of FIG. 1F, as shown in FIG. 1G at (c), thesegmented wavelength converting layer 1510 may be aligned with andattached to light emitting devices 1530. The gaps 1515 between thesegmented wavelength converting layers may correspond to the spacingbetween the light emitting devices 1530 such that the segmentedwavelength converting layers can be aligned with and attached to thelight emitting devices 1530. Light emitting devices 1530 may contain anactive light-emitting layer and may also contain n-contacts andp-contacts that enable current to activate the active light-emittinglayer. The wavelength converting layer 1510 and light emitting devices1530 may be cured via any applicable technique such as temperature basedcuring, polymer based curing, UV based curing, or the like.

According to step 1430 of FIG. 1F, as shown in FIG. 1G at (d), thecontiguous portion of the wavelength converting layer 1510 thatconnected the segmented wavelength converting layers may be removed. Theportion of wavelength converting layer 1510 may be removed using anyapplicable technique including via sawing, etching, applying a mask todice, using one or more lasers, chemical treatment, or the like, or bydicing as understood in the art. The dicing may result in individualpixels that contain light emitting devices 1530, and wavelengthconverting layers 1530, such that the pixels are not connected via thewavelength converting layer 1510.

As shown in FIG. 1G at (d), the light emitting devices 1530 with thesegmented wavelength converting layer 1510 (collectively, pixels) may beplaced on a tape 1535 which may be configured to restrict the leakage ofgas particles. As an example, the tape 1535 may be a kapton tape.According to step 1440 of FIG. 1G, an optical isolation material 1540may be applied to the pixels. The optical isolation material may beapplied via an atomic layer deposition (ALD) process. ALD is a techniquewhereby a material may be deposited onto a surface in a self-limitingmanner such that a thin coating or layer of the material is depositedinto the surface. As shown in FIG. 1G at (d), an optical isolationmaterial 1540 may be deposited onto the exposed surfaces of the pixelsincluding the sidewalls of the light emitting devices 1530, thesidewalls of the wavelength converting layers 1510.

As shown in FIG. 1G at (e) the pixels may be deposited onto a tape 1545configured to support component removal techniques. According to animplementation, tape 1535 and 1545 may be the same tape. According tostep 1450 of FIG. 1F, sacrificial portions 1540 of the wavelengthconverting layer 1510 distal from respective light emitting devices 1530as well as the optical isolation material 1540 on the top surface andsidewalls of the sacrificial portions 1540 of the wavelength convertinglayer may be removed. The sacrificial portions 1540 of the wavelengthconverting layer may be any subset of the wavelength converting layer1510 and may be, for example, approximately 1%, 10%, 20%, 30%, 40%, 50%,60%, 70%, 80%, 90%, or 99% of the wavelength converting layer 1510. Theremoval may be conducted via sawing, etching, applying a mask to dice,using one or more lasers, chemical treatment, or the like, or dicing asunderstood in the art. The resulting pixel may contain light emittingdevices 1530 with optical isolation material on their sidewalls andwavelength converting layers 1510 with optical isolation material ontheir sidewalls. As shown, the surface of the wavelength convertinglayers 1510 opposite the light emitting devices 1350 do not contain theoptical isolation material and the pixels may be configured to emitlight through this surface.

As shown in FIG. 1H, wavelength converting layers 1720 may be attachedto light emitting devices 1770 of an LED array 1700, to create pixels1775. Wavelength converting layers 1720 can be the same as or similar towavelength converting layers 1310 of FIG. 1E and/or 1510 of FIG. 1G.Light emitting devices 1770 may be the same as or similar to the lightemitting devices 1330 of FIG. 1E and/or 1530 of FIG. 1G. In FIG. 1N,light emitting devices 1770 may include GaN layer 1750, active region1790, contact 1780, pattern sapphire substrate (PSS) 1760, andwavelength converting layers 1720. The wavelength converting layers 1720are shown to include optical isolation material 1730 on the sidewalls ofthe wavelength converting layers 1720 but not on the surface distal tothe light emitting devices 1770, in accordance with the disclosureherein as any optical isolation material on this distal surface may beremoved along with removal of a sacrificial portion of the respectivewavelength converting layer. More specifically, the spacing createdbetween the pixels may correspond to gaps created during dicing, asdisclosed in FIGS. 1D-1G.

As shown in FIG. 1H, sidewall materials 1730 may be applied to thewavelength converting layers 1720. The wavelength converting layers 1720may be mounted over GaN layers 1750 and pattern sapphire substrate (PSS)patterns 1760 may be located between the GaN layers 1750 and thewavelength converting layers. Active regions 1790 may be configured toemit light at least partially towards the wavelength converting layers1720 and the light emitting devices 1770 may include contacts 1780.Optical isolator material 1740 may be applied to the sidewalls of theGaN layer 1750. The expandable film 1710 may be removed from thewavelength converting layers 1720, for example, after the wavelengthconverting layers 1720 have been attached to the light emitting devices1770.

As an example, the pixels 1775 of FIG. 1H may correspond to the pixels111 of FIG. 1A-C. Specifically, as shown in FIG. 1A, the pixels 111 maycorrespond to the pixels 1775 of FIG. 1N after the wavelength convertinglayers 1720 are mounted onto the light emitting devices 1770. When thepixels 111 or 1775 are activated, the respective active regions 1790 ofthe emitters may generate a light. The light may pass through thewavelength converting layers 1720 and may substantially be emitted fromthe surface of the pixels 1775 and light that reaches the sidewalls ofthe wavelength converting layers 1720 may not escape from the sidewallsdue to the sidewall materials 1730 and may be reflected when itintersects the sidewalls due to the sidewall materials 1730.

The pixels 1775 of FIG. 1H may be similar to the pixels 111 of FIG. 1A,and pixels 1010, 1020, and 1030 of FIG. 1B. The pixels 1775 of FIG. 1Hmay be part of an LED array 410 of FIG. 2A, as further disclosed herein.

FIG. 2A is a top view of an electronics board with an LED array 410attached to a substrate at the LED device attach region 318 in oneembodiment. The electronics board together with the LED array 410represents an LED system 400A. Additionally, the power module 312receives a voltage input at Vin 497 and control signals from theconnectivity and control module 316 over traces 418B, and provides drivesignals to the LED array 410 over traces 418A. The LED array 410 isturned on and off via the drive signals from the power module 312. Inthe embodiment shown in FIG. 2A, the connectivity and control module 316receives sensor signals from the sensor module 314 over trace 418C.

FIG. 2B illustrates one embodiment of a two channel integrated LEDlighting system with electronic components mounted on two surfaces of acircuit board 499. As shown in FIG. 2B, an LED lighting system 400Bincludes a first surface 445A having inputs to receive dimmer signalsand AC power signals and an AC/DC converter circuit 412 mounted on it.The LED system 400B includes a second surface 445B with the dimmerinterface circuit 415, DC-DC converter circuits 440A and 440B, aconnectivity and control module 416 (a wireless module in this example)having a microcontroller 472, and an LED array 410 mounted on it. TheLED array 410 is driven by two independent channels 411A and 411B. Inalternative embodiments, a single channel may be used to provide thedrive signals to an LED array, or any number of multiple channels may beused to provide the drive signals to an LED array.

The LED array 410 may include two groups of LED devices. In an exampleembodiment, the LED devices of group A are electrically coupled to afirst channel 411A and the LED devices of group B are electricallycoupled to a second channel 411B. Each of the two DC-DC converters 440Aand 440B may provide a respective drive current via single channels 411Aand 411B, respectively, for driving a respective group of LEDs A and Bin the LED array 410. The LEDs in one of the groups of LEDs may beconfigured to emit light having a different color point than the LEDs inthe second group of LEDs. Control of the composite color point of lightemitted by the LED array 410 may be tuned within a range by controllingthe current and/or duty cycle applied by the individual DC/DC convertercircuits 440A and 440B via a single channel 411A and 411B, respectively.Although the embodiment shown in FIG. 2B does not include a sensormodule (as described in FIG. 2A), an alternative embodiment may includea sensor module.

The illustrated LED lighting system 400B is an integrated system inwhich the LED array 410 and the circuitry for operating the LED array410 are provided on a single electronics board. Connections betweenmodules on the same surface of the circuit board 499 may be electricallycoupled for exchanging, for example, voltages, currents, and controlsignals between modules, by surface or sub-surface interconnections,such as traces 431, 432, 433, 434 and 435 or metallizations (not shown).Connections between modules on opposite surfaces of the circuit board499 may be electrically coupled by through board interconnections, suchas vias and metallizations (not shown).

According to embodiments, LED systems may be provided where an LED arrayis on a separate electronics board from the driver and controlcircuitry. According to other embodiments, a LED system may have the LEDarray together with some of the electronics on an electronics boardseparate from the driver circuit. For example, an LED system may includea power conversion module and an LED module located on a separateelectronics board than the LED arrays.

According to embodiments, an LED system may include a multi-channel LEDdriver circuit. For example, an LED module may include embedded LEDcalibration and setting data and, for example, three groups of LEDs. Oneof ordinary skill in the art will recognize that any number of groups ofLEDs may be used consistent with one or more applications. IndividualLEDs within each group may be arranged in series or in parallel and thelight having different color points may be provided. For example, warmwhite light may be provided by a first group of LEDs, a cool white lightmay be provided by a second group of LEDs, and a neutral white light maybe provided by a third group.

FIG. 2C shows an example vehicle headlamp system 300 including a vehiclepower 302 including a data bus 304. A sensor module 307 may be connectedto the data bus 304 to provide data related to environment conditions(e.g. ambient light conditions, temperature, time, rain, fog, etc),vehicle condition (parked, in-motion, speed, direction),presence/position of other vehicles, pedestrians, objects, or the like.The sensor module 307 may be similar to or the same as the sensor module314 of FIG. 2A. AC/DC Converter 305 may be connected to the vehiclepower 302.

The AC/DC converter 312 of FIG. 2C may be the same as or similar to theAC/DC converter 412 of FIG. 2B and may receive AC power from the vehiclepower 302. It may convert the AC power to DC power as described in FIG.2B for AC-DC converter 412. The vehicle head lamp system 300 may includean active head lamp 330 which receives one or more inputs provided by orbased on the AC/DC converter 305, connectivity and control module 306,and/or sensor module 307. As an example, the sensor module 307 maydetect the presence of a pedestrian such that the pedestrian is not welllit, which may reduce the likelihood that a driver sees the pedestrian.Based on such sensor input, the connectivity and control module 306 mayoutput data to the active head lamp 330 using power provided from theAC/DC converter 305 such that the output data activates a subset of LEDsin an LED array contained within active head lamp 330. The subset ofLEDs in the LED array, when activated, may emit light in the directionwhere the sensor module 307 sensed the presence of the pedestrian. Thesesubset of LEDs may be deactivated or their light beam direction mayotherwise be modified after the sensor module 207 provides updated dataconfirming that the pedestrian is no longer in a path of the vehiclethat includes vehicle head lamp system.

FIG. 3 shows an example system 550 which includes an applicationplatform 560, LED systems 552 and 556, and optics 554 and 558. The LEDSystem 552 produces light beams 561 shown between arrows 561 a and 561b. The LED System 556 may produce light beams 562 between arrows 562 aand 562 b. In the embodiment shown in FIG. 3, the light emitted from LEDSystem 552 passes through secondary optics 554, and the light emittedfrom the LED System 556 passes through secondary optics 558. Inalternative embodiments, the light beams 561 and 562 do not pass throughany secondary optics. The secondary optics may be or may include one ormore light guides. The one or more light guides may be edge lit or mayhave an interior opening that defines an interior edge of the lightguide. LED systems 552 and/or 556 may be inserted in the interioropenings of the one or more light guides such that they inject lightinto the interior edge (interior opening light guide) or exterior edge(edge lit light guide) of the one or more light guides. LEDs in LEDsystems 552 and/or 556 may be arranged around the circumference of abase that is part of the light guide. According to an implementation,the base may be thermally conductive. According to an implementation,the base may be coupled to a heat-dissipating element that is disposedover the light guide. The heat-dissipating element may be arranged toreceive heat generated by the LEDs via the thermally conductive base anddissipate the received heat. The one or more light guides may allowlight emitted by LED systems 552 and 556 to be shaped in a desiredmanner such as, for example, with a gradient, a chamfered distribution,a narrow distribution, a wide distribution, an angular distribution, orthe like.

In example embodiments, the system 550 may be a mobile phone of a cameraflash system, indoor residential or commercial lighting, outdoor lightsuch as street lighting, an automobile, a medical device, AR/VR devices,and robotic devices. The LED System 400A shown in FIG. 2A and vehiclehead lamp system 300 shown in FIG. 2C illustrate LED systems 552 and 556in example embodiments.

The application platform 560 may provide power to the LED systems 552and/or 556 via a power bus via line 565 or other applicable input, asdiscussed herein. Further, application platform 560 may provide inputsignals via line 565 for the operation of the LED system 552 and LEDsystem 556, which input may be based on a user input/preference, asensed reading, a pre-programmed or autonomously determined output, orthe like. One or more sensors may be internal or external to the housingof the application platform 560. Alternatively or in addition, as shownin the LED system 400 of FIG. 2A, each LED System 552 and 556 mayinclude its own sensor module, connectivity and control module, powermodule, and/or LED devices.

In embodiments, application platform 560 sensors and/or LED system 552and/or 556 sensors may collect data such as visual data (e.g., LIDARdata, IR data, data collected via a camera, etc.), audio data, distancebased data, movement data, environmental data, or the like or acombination thereof. The data may be related a physical item or entitysuch as an object, an individual, a vehicle, etc. For example, sensingequipment may collect object proximity data for an ADAS/AV basedapplication, which may prioritize the detection and subsequent actionbased on the detection of a physical item or entity. The data may becollected based on emitting an optical signal by, for example, LEDsystem 552 and/or 556, such as an IR signal and collecting data based onthe emitted optical signal. The data may be collected by a differentcomponent than the component that emits the optical signal for the datacollection. Continuing the example, sensing equipment may be located onan automobile and may emit a beam using a vertical-cavitysurface-emitting laser (VCSEL). The one or more sensors may sense aresponse to the emitted beam or any other applicable input.

In example embodiment, application platform 560 may represent anautomobile and LED system 552 and LED system 556 may representautomobile headlights. In various embodiments, the system 550 mayrepresent an automobile with steerable light beams where LEDs may beselectively activated to provide steerable light. For example, an arrayof LEDs may be used to define or project a shape or pattern orilluminate only selected sections of a roadway. In an exampleembodiment, Infrared cameras or detector pixels within LED systems 552and/or 556 may be sensors (e.g., similar to sensors module 314 of FIG.2A and 307 of FIG. 2C) that identify portions of a scene (roadway,pedestrian crossing, etc.) that require illumination.

Having described the embodiments in detail, those skilled in the artwill appreciate that, given the present description, modifications maybe made to the embodiments described herein without departing from thespirit of the inventive concept. Therefore, it is not intended that thescope of the invention be limited to the specific embodimentsillustrated and described. Although features and elements are describedabove in particular combinations, one of ordinary skill in the art willappreciate that each feature or element can be used alone or in anycombination with the other features and elements. In addition, themethods described herein may be implemented in a computer program,software, or firmware incorporated in a computer-readable medium forexecution by a computer or processor. Examples of computer-readablemedia include electronic signals (transmitted over wired or wirelessconnections) and computer-readable storage media. Examples ofcomputer-readable storage media include, but are not limited to, a readonly memory (ROM), a random access memory (RAM), a register, cachememory, semiconductor memory devices, magnetic media such as internalhard disks and removable disks, magneto-optical media, and optical mediasuch as CD-ROM disks, and digital versatile disks (DVDs).

The invention claimed is:
 1. A method for making a pixelated array ofwavelength converted light emitting devices, the method comprising:providing a wavelength converting structure comprising a wavelengthconverting layer having a first surface and a carrier layer having afirst surface and an oppositely positioned second surface, the firstsurface of the wavelength converting layer disposed on the first surfaceof the carrier layer, the wavelength converting structure comprisinggaps extending completely through the wavelength converting layer andpartially through the carrier layer perpendicular to the first surfaceof the carrier layer to define at least a first segment of thewavelength converting structure having a first structure surfaceopposite from the first surface of the carrier layer and a secondsegment of the wavelength converting structure having a second segmentsurface opposite from the first surface of the carrier layer; afterproviding the wavelength converting structure, attaching a first lightemitting device to the first segment surface of the first segment andattaching a second light emitting device to the second segment surfaceof the second segment; removing a portion of the carrier layer startingfrom the second surface of the carrier layer to open ends of the gaps todefine at least a first pixel from the first segment and the first lightemitting device and a second pixel from the second segment and thesecond light emitting device; disposing an optical isolation material onexposed surfaces of each of the first pixel and the second pixel; andremoving remaining portions of the carrier layers from the first pixeland the second pixel along with portions of the optical isolationmaterial disposed on the remaining portions of the carrier layer.
 2. Themethod of claim 1, wherein providing the wavelength converting structurecomprises dicing the wavelength converting layer and the carrier layerto form the gaps.
 3. The method of claim 2, wherein providing thewavelength converting structure further comprises attaching thewavelength converting layer to the carrier layer before dicing thewavelength converting layer and the carrier layer.
 4. The method ofclaim 1, further comprising curing the first pixel and the second pixelbefore removing the portion of the carrier layer.
 5. The method of claim1, further comprising transferring the first pixel and the second pixelonto at least one of a kapton tape or a grinding tape before disposingthe optical isolation material.
 6. The method of claim 1, wherein thewavelength converting layer is selected from a phosphor in glass, aphosphor in silicone, and a phosphor ceramic.
 7. The method of claim 1,wherein the optical isolation material is selected from a distributedBragg reflector (DBR), a reflective material, and an absorptivematerial.
 8. The method of claim 1, wherein a coefficient of thermalexpansion (CTE) of the carrier layer is substantially matched to a CTEof the wavelength converting layer.
 9. The method of claim 1, whereinthe optical isolation material is disposed using an atomic layerdeposition (ALD) technique.
 10. The method of claim 1, wherein the firstpixel is less than 500 microns wide.